THE FORTIETH L. RAY BUCKENDALE LECTURE Diesel Engine Design for the 1990s SP-1011 (940130)

Merrion, David F.

doi:10.4271/940130

Cited by 5 publications

(1 citation statement)

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“…Speed Versus Time Plot for the Central Business District (CBD) Cycle.WVU 5-Peak CycleThe WVU 5-Peak Cycle is also called the WVU Truck Cycle. This cycle was developed by the research group at the Transportable Heavy-Duty Vehicle Emissions Testing Laboratory in West Virginia University in 1994(9). The WVU 5-Peak Cycle is designed for general truck chassis testing for comparison of diesel and alternate fuels.…”

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Real world heavy-duty vehicle emissions modeling

Andrei¹

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Heavy-duty vehicle emissions represent a significant portion of the mobile source emissions inventory. Accurate estimation of their contribution is essential as on-highway and non-road heavy-duty diesel emissions account for at least one third of the oxides of nitrogen (NO x) in the inventory. West Virginia University (WVU) has developed an extensive database of continuous transient gaseous emissions levels from a wide variety of heavy-duty vehicles in field operation. The database was built using WVU Transportable Heavy-Duty Vehicle Emissions Testing Laboratories (THDVETL). Several different transient cycles were utilized for testing including the Central Business District (CBD) schedule. Present day vehicle tailpipe emissions inventory approaches fail to consider directly the influence of terrain and road grade on the inventory. The behavior of a heavyduty class 8 tractor truck, a medium-duty class 6 box truck and a heavy-duty class 8 transit bus over roads with varying grades were simulated in order to predict NO x , CO 2 , CO and PM emissions. As expected, road grade has a modest but significant effect on NO x and CO 2 emissions (especially when the road is very steep), but a more substantial effect on CO and PM emissions. These results were obtained based on the simulation of the considered vehicles over roads with different grades (0% (flat land),-2%, +2%,-5% and +5%) and over sinusoidal roads with a maximum grade between 0% and 7%. The road grade has a modest but significant effect on NO x and CO 2 emissions, especially when the road is very steep (road grade greater than 2%), but a substantial effect on CO emissions. Like CO, PM emissions are very much influenced by the road grade especially if the road is very steep because these emissions increase substantially near full engine load. As it is well known vehicles emissions in g/bhp-hr are infinite at idle. Also known is that vehicles emissions are often high due to high load (1/2 ρ a C D A V 3) at high speeds. All these show the necessity of the development of speed correction factors to be used in inventory purposes. Several speed correction factors were developed for the three vehicles considered in this analysis. These correction factors can be used to account the variations in the vehicle condition, class and variations in the testing environment.

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